add a few useful functions

src/Graphics/RefreshStructs.cs

@@ -281,6 +281,24 @@ namespace MoonWorks.Graphics
 			StencilStoreOp = StoreOp.DontCare;
 		}
 
+		public DepthStencilAttachmentInfo(
+			Texture texture,
+			LoadOp loadOp = LoadOp.DontCare,
+			StoreOp storeOp = StoreOp.Store,
+			LoadOp stencilLoadOp = LoadOp.DontCare,
+			StoreOp stencilStoreOp = StoreOp.Store
+		) {
+			Texture = texture;
+			Depth = 0;
+			Layer = 0;
+			Level = 0;
+			DepthStencilClearValue = new DepthStencilValue();
+			LoadOp = loadOp;
+			StoreOp = storeOp;
+			StencilLoadOp = stencilLoadOp;
+			StencilStoreOp = stencilStoreOp;
+		}
+
 		public Refresh.DepthStencilAttachmentInfo ToRefresh()
 		{
 			return new Refresh.DepthStencilAttachmentInfo

src/Graphics/State/VertexInputState.cs

@@ -8,6 +8,12 @@
 		public VertexBinding[] VertexBindings;
 		public VertexAttribute[] VertexAttributes;
 
+		public VertexInputState()
+		{
+			VertexBindings = new VertexBinding[0];
+			VertexAttributes = new VertexAttribute[0];
+		}
+
 		public VertexInputState(
 			VertexBinding vertexBinding,
 			params VertexAttribute[] vertexAttributes

src/Math/MathHelper.cs

@@ -280,6 +280,11 @@ namespace MoonWorks.Math
 			return result;
 		}
 
+		public static float Quantize(float value, float step)
+		{
+			return (float) System.Math.Floor(value / step) * step;
+		}
+
 		/// <summary>
 		/// Converts radians to degrees.
 		/// </summary>